1. Field of the Invention
The present invention relates to a printed circuit board having jumper lines and a method for making the printed circuit board, wherein the planar jumper layer may be made simultaneously during fabrication of the printed circuit board, without having to perform the wire-bonding work.
2. Description of the Related Art
A conventional printed circuit board often needs to use jumpers for reasons of the layout of the circuit.
A conventional coplanar waveguide (C.P.W.) fed uni-planar bow-tie antenna of a microwave circuit of a printed circuit board in accordance with the prior art is shown in FIG. 1.
A conventional Lange coupler of a microwave circuit of a printed circuit board in accordance with the prior art is shown in FIG. 2.
The above microwave circuit comprises a dielectric substrate 12, a metallic ground layer 11 mounted on the bottom side of the dielectric substrate 12, a line layer 13 mounted on the top side of the dielectric substrate 12, and jumpers 14 mounted on the line layer 13.
A conventional coplanar waveguide (C.P.W.) of a microwave circuit of a printed circuit board in accordance with the prior art is shown in FIG. 3. The metallic ground layer 11 is mounted on one side of the dielectric substrate 12, and jumpers 14 are mounted on the metallic ground layer 11.
The jumpers 14 are formed by performing a wire-bonding work, so that after the microwave circuit of the printed circuit board is made, it is necessary to perform a wire-bonding work to form the jumpers 14, thereby causing inconvenience during fabrication and increasing cost of fabrication. In addition, the jumpers cannot be used in the inner layer of a multi-layer printed circuit board.
On the other hand, the printed circuit board includes multiple microwave circuits, such as the power distributors, the couplers, the wave filters, the wavelength converters, the modulators or the like. The wavelength of the microwave is very short, so that the wavelength of the microwave and the size of the microwave circuit belong to the same grade. Thus, many electrical parameters, such as resistance, reluctance, capacitance, conductance or the like, that may be omitted in the low-frequency alternating circuit, have to be considered in the microwave circuit. Change of the size of the microwave circuit will affect the values of the above-mentioned electrical parameters. The microwave circuit may maintain its function only at a determined wavelength (or frequency) and size, so that when the size of the microwave circuit is changed, the microwave circuit will lose its function. Thus, the size of the microwave circuit cannot be shortened arbitrarily, so that the microwave circuit occupies a considerable space in the printed circuit board. Therefore, the printed circuit board cannot be miniaturized, so that it cannot satisfy the requirements of light, thin, short and small designs.
Traditionally, a microwave circuit includes multiple transmission lines with proper sizes to form a proper geometry.
The wavelength of the microstrip transmission line of the line layer 13 can be calculated as flows:
xcexgxc3x97f=c/{square root over ( )}xcex5eff
Wherein, c is the velocity of light, and is equal to 3108 m/sec, xcex5eff is the effective dielectric constant, f is the frequency of the electromagnetic wave, and xcexg is the wavelength of the electromagnetic wave under this effective dielectric constant.
It is known from the above equation that, when the frequency is fixed, if the effective dielectric constant is increased, the wavelength of the electromagnetic wave under this effective dielectric constant may be shortened. Thus, the size of the microwave circuit that is proportional to the wavelength may be shortened. Therefore, when the effective dielectric constant is increased, the size of the microwave circuit may be shortened.
Further, when the media of the microstrip transmission line or the microwave circuit are not even, it is assumed that the equivalent media of the microstrip transmission line or the microwave circuit are even, and the dielectric constant of the equivalent media is the effective dielectric constant xcex5eff. The effective dielectric constant may be calculated as follows:
xcex5eff=Csubstrate/Cair
wherein, Csubstrate is the capacitance of the microstrip transmission line or the non-metallic part of the microwave circuit after being filled with the media, and Cair is the capacitance of the air.
At this time, distribution of the dielectric media may be not even, and the microstrip transmission line or the non-metallic part of the microwave circuit is filled with the capacitance of the air. If distribution of the dielectric media is not even, and the dielectric media consist of two dielectric materials, wherein one dielectric material has a higher dielectric constant, and the other has a lower dielectric constant, such that the effective dielectric constant is between the two dielectric constants. Thus, a high dielectric value material may be coated on the entire line layer of the microwave circuit, or coated on partial transmission lines of the line layer, thereby increasing the effective dielectric constant, so as to shorten the size of the microwave circuit, without affecting the electrical function of the microwave circuit.
The primary objective of the present invention is to provide a printed circuit board having jumper lines, and a method for making the printed circuit board. An isolation layer made of a dielectric material is coated on the line layer of the printed circuit board, and multiple pads are formed in the isolation layer, thereby exposing part of the line layer without covered by the isolation layer. A high conductive material is coated on the isolation layer to connect the multiple pads, thereby forming a planar jumper layer that is connected to the line layer through the circular pads. Thus, the planar jumper layer may be made simultaneously during fabrication of the printed circuit board, without having to perform the wire-bonding work.
In accordance with a first aspect of the present invention, there is provided a method for making a printed circuit board having jumper lines, comprising the steps of:
a) making a printed circuit board;
b) coating or printing a dielectric material on the printed circuit board to form an isolation layer;
c) forming multiple pads in the isolation layer of the dielectric material, thereby exposing part of the printed circuit board without covered by the dielectric material; and
d) coating or printing a high conductive material on the isolation layer of the dielectric material to connect the multiple pads, thereby forming a planar jumper layer that is connected to the printed circuit board through the circular pads.
In accordance with a second aspect of the present invention, there is provided a method for making a printed circuit board having jumper lines, comprising the steps of:
a) determining a pre-estimated value of an effective dielectric constant;
b) determining a shortened size of a microwave circuit according to the pre-estimated value of the effective dielectric constant and a used working frequency;
c) providing a dielectric substrate that may increase the effective dielectric constant to the pre-estimated value;
d) making the microwave circuit with a shortened size on the dielectric substrate;
e) coating or printing an isolation layer on the microwave circuit;
f) forming multiple pads in the isolation layer, thereby exposing part of the microwave circuit without covered by the isolation layer; and
g) coating or printing a high conductive material on the isolation layer to connect the multiple pads, thereby forming a planar jumper layer that is connected to the microwave circuit through the circular pads.
In accordance with a third aspect of the present invention, there is provided a printed circuit board having jumper lines, comprising: a line layer, an isolation layer made of a dielectric material coated on the line layer, multiple pads formed in the isolation layer, thereby exposing part of the line layer without covered by the isolation layer, and a high conductive material coated on the isolation layer to connect the multiple pads, thereby forming a planar jumper layer that is connected to the line layer through the circular pads.
In accordance with a fourth aspect of the present invention, there is provided a printed circuit board having jumper lines, comprising: a dielectric substrate, a metallic ground layer mounted on a first side of the dielectric substrate, and a line layer mounted on a second side of the dielectric substrate, an isolation layer made of a high dielectric value material coated on the line layer, multiple pads formed in the isolation layer, thereby exposing part of the line layer without covered by the isolation layer, and a high conductive material coated on the isolation layer to connect the multiple pads, thereby forming a planar jumper layer that is connected to the line layer through the circular pads.
In accordance with a fifth aspect of the present invention, there is provided a printed circuit board having jumper lines, comprising: a dielectric substrate, a metallic ground layer mounted on one side of the dielectric substrate, an isolation layer made of a high dielectric value material coated on the metallic ground layer, multiple pads formed in the isolation layer, thereby exposing part of the metallic ground layer without covered by the isolation layer, and a high conductive material coated on the isolation layer to connect the multiple pads, thereby forming a planar jumper layer that is connected to the metallic ground layer through the circular pads.
In accordance with a sixth aspect of the present invention, there is provided a printed circuit board having jumper lines, comprising: a dielectric substrate made of a high dielectric value material, a metallic ground layer mounted on a first side of the dielectric substrate, a line layer mounted on a second side of the dielectric substrate, an isolation layer coated on the line layer, multiple pads formed in the isolation layer, thereby exposing part of the line layer without covered by the isolation layer, and a high conductive material coated on the isolation layer to connect the multiple pads, thereby forming a planar jumper layer that is connected to the line layer through the circular pads.
In accordance with a seventh aspect of the present invention, there is provided a printed circuit board having jumper lines, comprising: a dielectric substrate made of a high dielectric value material, a metallic ground layer mounted on one side of the dielectric substrate, an isolation layer coated on the metallic ground layer, multiple pads formed in the isolation layer, thereby exposing part of the metallic ground layer without covered by the isolation layer, and a high conductive material coated on the isolation layer to connect the multiple pads, thereby forming a planar jumper layer that is connected to the metallic ground layer through the circular pads.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.